Our SOP....
Our SOP requires that we check the altimeters on the ground as part of the instrument check.
Then, we do the check at transition altitude.
Then, we do the check at TOC.
Then, we do the check APPROXIMATELY every hour thereafter.
However, the ONLY check we make that is RECORDED is the TOC check.
Note: if we change altitudes (e.g. step climb at some point in cruise), we do another check that is also recorded.
Again, the cruise altitude INITIALLY is recorded. Other than that, it's just
a check that is verbalized by the pilots.
Also note: the recording at TOC includes the Standby Altimeter reading.
The way I read the regulations (MNPS over the Atlantic, etc.) is that the hourly checks need not necessarily be recorded.....
This is my company's SOP. Other companies may vary.